The mining industry employs ore and concentrate pipes to transport ores, concentrates, tailings and other materials over long distances. Such pipes can be constructed from metal/metallic sections joined together to form an extended pipeline, and the ores being conveyed can often be in the form of wet slurries or even dry particulate solids.
Many changes of direction can occur along the path of such pipelines, both in the vertical and in the horizontal plane, requiring the use of elbows and bends. Some such elbows and bends can turn the pipeline up to angles of 180°, for example, in energy dissipation stations used with pipelines that fall from elevations exceeding 500 meters.
When transporting material such as abrasive/erosive/corrosive slurries, concentrates, tailings, a high level of pipe erosion can occur, especially at any bends in the pipeline, and most especially where the bends are located at the end of a pipeline fall. To avoid wear and/or corrosion, the piping can be internally coated with an elastomeric material (e.g. rubber, or a synthetic material such as polyurethane or the like).
Pipe diameters in such pipelines can vary between 50 and 500 mm, with it being desirable for each given pipe diameter to have a continuous coating of elastomeric material throughout its length. In some instances a specific uniform thickness is desirable and the coating thickness is selected specifically to the pipe diameter.
Coatings of rubber are most used for coarse particulate materials with a size above 2 mm due to the better resistance afforded by rubber at such particle sizes. For smaller particle size materials, polyurethane offers better resistance to abrasion. Thus, for materials such as concentrates and tailings, usually polyurethane is used as the coating material.
A uniform coating is more easily applied to straight sections of pipe, but less so in the bends and elbows, where it is difficult to achieve a uniform thickness, especially when the coating to be applied is of a synthetic type, such as polyurethane.